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  1. #1
    Join Date
    Dec 2007
    Location
    Chandler AZ
    Posts
    168

    Walk-in Cooler Help Please

    got a call on a walk in cooler not keeping temp. R22 unit , condenser on roof ,low 62 psi , high 360 psi ,hose down cond coil ,check fan motor ,blade rotation ,still the same . Could be non-condensible in system . Pulled charge ,replace dryer ,vacuum to 250 mircon ,charge unit and still the same .

    ODT 109
    low 62 psi
    high 360 psi
    discharge line temp 235
    liquid line temp 125
    suction line temp 62
    cond enter air temp 109
    cond discharge air temp 129

    low pressure on evp. 62 psi
    suction line temp after evp 49
    box temp 45
    Any suggestions

    Thanks

  2. #2
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,400

  3. #3
    Join Date
    Nov 2005
    Location
    Haymarket VA
    Posts
    642
    Quote Originally Posted by crazy eye View Post
    got a call on a walk in cooler not keeping temp. R22 unit , condenser on roof ,low 62 psi , high 360 psi ,hose down cond coil ,check fan motor ,blade rotation ,still the same . Could be non-condensible in system . Pulled charge ,replace dryer ,vacuum to 250 mircon ,charge unit and still the same .

    ODT 109
    low 62 psi
    high 360 psi
    discharge line temp 235
    liquid line temp 125
    suction line temp 62
    cond enter air temp 109
    cond discharge air temp 129

    low pressure on evp. 62 psi
    suction line temp after evp 49
    box temp 45
    Any suggestions

    Thanks
    overcharge
    clean coil with cleaner
    and check your txv why not closing
    13* superheat is high

  4. #4
    Join Date
    May 2009
    Location
    In the Hudson Valley of New York
    Posts
    1,815
    Could be an inefficient compressor? Did you try a pump down test with the SSV? Are the amps much lower then RLA? I have run into a few R-22 WI coolers, running that kind of suction pressure, I found the compressor was inefficient. But I also see you work in a much hotter ambient then I am used to.

  5. #5
    Join Date
    May 2009
    Location
    watertown ny
    Posts
    32
    if you pulled the correct micron and have correct charge in it and all checks out ok with the condenser id lean towards compressor.did you try pumping system down> your high side should not rise unless its over charged then could be a (boom!)

  6. #6
    Join Date
    Mar 2009
    Location
    Spokane WA
    Posts
    299

    Wink

    I would guess that you are overcharged a little and you are picking up quite a bit of extra heat across the compressor.

    Do you have a suction accumulator on the system? If so you can run the superheat down to about 8* at the compressor.

    Your discharge temp is way high. 235* is starting to cause the oil to do so real bad things in the system. Which oil is in the system if you know? You should be able to calculate the liquid line temperature by looking at the ODT, superheat and heat of compression. With the TP chart it looks to me like your discharge pressure is about 60* high. You subcooling is high too so that supports the overcharged theory. Probably good around 12* subcooling. You may have about 20% of the condenser stacked with liquid refrigerant.

    If you can dump that extra heat from the refrigerant and get the superheat where it needs to be you should be in fat city!

    Good Luck,
    JJ

    P.S. The extra heat from the windings is what I was getting at about the high discharge temperature. On R-22 systems I don't like to see the discharge temperature above 210 Deg F. That is when the oil starts breaking down and leaving carbon if it is the older style oil.
    Last edited by Super Tech JJ; 07-09-2009 at 05:17 PM. Reason: another thought!

  7. #7
    Join Date
    Nov 2005
    Location
    Haymarket VA
    Posts
    642
    Agree with Super Tech

  8. #8
    Join Date
    Jun 2009
    Posts
    92
    check txv heating bulb, adjust it to open and close

  9. #9
    Join Date
    Jul 2005
    Location
    FLORIDA
    Posts
    1,163
    your head is effecting your suction, 360 is about right for old condenser 110 + 35 degrees = 145 condensing temp r-22 =359 psi

    super heat is 14 degrees should be between 6 and 8

    is this box outside in these temps is so its needs some cover from sun

    i would also check condenser fan blade position you might get it closer to 25 degree condensing temp if someone installed it wrong and check the shroud around it...... make sure both coils are clean also so its feeding enough gas dirty evap and txv will close down and not feed

    you only need about 5 degree and it was maxed out when design for these temps so it has to be spotless and set properly to maintain during high loads

    no model # or compressor # and size of box and location for a load calc.would help alot
    once you think you've seen it all
    (THINK AGAIN)
    I would rather work for free than be look upon as a thief!!!!!

  10. #10
    Join Date
    Nov 2005
    Location
    Haymarket VA
    Posts
    642
    Quote Originally Posted by dirtyboy103us View Post
    your head is effecting your suction, 360 is about right for old condenser 110 + 35 degrees = 145 condensing temp r-22 =359 psi

    super heat is 14 degrees should be between 6 and 8

    is this box outside in these temps is so its needs some cover from sun

    i would also check condenser fan blade position you might get it closer to 25 degree condensing temp if someone installed it wrong and check the shroud around it...... make sure both coils are clean also so its feeding enough gas dirty evap and txv will close down and not feed

    you only need about 5 degree and it was maxed out when design for these temps so it has to be spotless and set properly to maintain during high loads

    no model # or compressor # and size of box and location for a load calc.would help alot
    35* condensor split High
    rule off thumb no more than 30*

  11. #11
    is there a head master?, receiver?, sight glass on this unit?

  12. #12
    Join Date
    Jul 2005
    Location
    FLORIDA
    Posts
    1,163
    Quote Originally Posted by sarpanch2001 View Post
    35* condensor split High
    rule off thumb no more than 30*

    but as they age and loose their efficiency and get a little dirty that goes out the window
    once you think you've seen it all
    (THINK AGAIN)
    I would rather work for free than be look upon as a thief!!!!!

  13. #13
    Join Date
    Dec 2006
    Location
    Middle Tennessee
    Posts
    11,347

    *

    Quote Originally Posted by 2001 View Post
    Could be an inefficient compressor?
    with 360 psi head pressure

    that compressor sounds like it's pumping to me



    .

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